Dash-pot



Patented Nov. 25, 1952 DASH-POT John Frank Pezdic, Saddle River Township, Bergen Count-y, N. J., assignor to The Torsion Balance Company, Clifton, N. J., a corporation of New York Application April 19, 1950, Serial No. 156,825

1 claim. l

The present invention relates to a dash-pot for damping the oscillations of ascale beam of a weighing scale, balance and the like, and aims to provide certain improvements in such devices. Dash-pots using air or hydraulic fluid have long been used lin scales and balances, the hydraulically operated dash-pots being the more efficient. Accordingly, it is preferable to use dash-pots containing hydraulic fluid to those employing air in balances where it is desired to obtain rapid damping of the oscillations of the beam. The hydraulic iiuid most usually used in dash-pots is oil and, to avoid spillage thereof when shipping or repairing a balance, means have been provided for sealing the oil within the dash-pot cylinder. How-ever, so far as I am aware, all such oil spillage preventing means have been of a character which required removing the balance case or enclosing housingr to gain access to the dash-pot, a procedure which was time-consuming and frequently required special tools which were not readily available.

The primary object of the present invention is to provide a weighing scale or balance provided with a dash-pot using hydraulic iiuid as the damping medium and having means accessible from the exterior of the balance case or enclosing housing for sealing the hydraulic iluid within the dash-pot cylinder during shipment of the balance or when making repairs thereto. A further object of the invention is to provide dash-pot cylinder sealing means which are operable from the exterior of the balance housing without the 4aid of any tools. A still further Object is to generally improve the constru-ction t of a dash-pot for a scale or the like and the mounting of the dash-pot so that the plunger will at all times move coaxially with the cylin` der during oscillation of the balance beam.

The foregoing and other objects of the inven- 'ff tion not specically enumerated, and the invention in its general aspects, will be better understood from the detailed description which follows, when considered in connection with the accompanying drawings, wherein:

Figure l is a front elevation of a balance or Weighing scale operating on the torsion principle and embodying the present invention, part of the bal-ance casing and cover being broken away to better illustrate constructional details.

Fig. 2 is a side elevation view of the weighing scale, the casing and cover being removed.

Fig. 3 is an enlarged diametrical section through the dash-pot and specifically illustrating the means for sealing the cylinder to pre- (Cl. 18S-100) 2 vent spillage of oil therefrom during shipment and repair.

Referring to the drawings, the invention, by way of illustration, is shown as applied to a Weighing scale or balance operating on the torsion principle, the essential parts of which are a base I 0 provided with a foot II and a pair of leveling screws I2, a substantially centrally disposed truss I3 rigidly mounted on the base and having a torsion spring I4 encircling the truss, a pair of balance arms I5 constituting the balance beam secured to the top and bottom of said torsion spring, said arms adjacent their opposite ends being secured to torsion springs I4a mounted upon oating trusses simi lar to the truss I3, and balance pans I6 supported by the floating trusses in a manner Well known in the art. For dampening the oscillations of the balance beam, which will oscillate about the torsion spring I 4 when unequal weights are applied to the balance pans, a dash-pot I 1 is connected with one or each of the end trusses of the balance. For arresting and releasing the end trusses suitable arresting means I8 are provided, said arresting means being operable by a rod I9 provided with a knurled finger piece ISa in a conventional manner.

The dash-pot I'I consists essentially of a cylinder 2! and a plunger 2|, said plunger comprising a piston 22 of any preferred type, for example, one having openings 23 therethrough, and a piston rod 24 secured at its inner end to the piston by a pair of lock nuts 25 or equivalent means, and at its opposite end being iiattened, as shown at 2B, and held within the bifurcated end 2'I of a bent rod 28, the opposite end of said rod being xedly secured to an end truss by a pair of lock nuts 29 or equivalent means. The cylinder 2D at its upper end is open and is partially closed by a cap 30 having an external, screw-threaded tubular extension 3l through which the piston rod 24 is freely movable, and at its lower end is closed and formed with a screw-threaded extension 32 terminating in a milled, nger-engageable end 33. The screwthreaded extension 32 is threaded through a screw-threaded opening 34 in the top of the base lil. Fixedly carried by the piston rod 24 adjacent its flattened end 26 is a cup 35 having a diameter to freely pass over the cylinder cap 3o, said cup having an internal screw-threaded extension 36 in the base of which is mounted a packing gasket 3l adapted to form a seal with the outer end of the tubular extension 3l when the latter is threaded home into the extension 3 36, such threading home being accomplished by manual rotation of the screw-threaded extension 32 on the cylinder 20.

A housing such as 38 engages over the base l0 and encloses the beam, the dash-pot and their associated parts for protecting the same against the entrance of dirt and foreign matter. If desirablefay cover A 39 mayabe hingedly aconnectedfto the housing to normally'protect the balance'- pans I6 when the balance is not in use.

A'thereof'renga-ges and provides a-seal Withthe packing' 31 vin the extension 36 of thefz-'cupfi lWhen the scale is tolbereadied Vforuseaftr iinfpacking'forafter .-vrepair;z it is setupifig'htfthe screws-threaded?extension: 32SY is rotated ein `l lthe 4.opposite 'directon-untilfthef base offfthe cylinder Q20l firmly seats Avagainst the top `Aof the base Ti 0. It lwill-.ft-husbe seen-."t-hat by assimplermanipulaage ofe'oil from the fdash-pot'can beI preventedfin axquicle and acile manner. f ff '-1Althoughllhavefshownand described the invention as applied.' to fa': weighingis'ca'le Vor balent" invention4 may b'e'applied -toahydrauliea-ily -op'erab'lefdashf-lpot@associated WithSa'ny'I-movable :member inhichftis'fxeneios'ed Witnina' nou-sing.

Heneef-whlefrhaveshwnfarrddescribedla' single application. oiinventon; Y'toire understood Y n the cylinder- .tioni offthe screwethreadedextensiorr 32 from :the 90 i r. e; y exteriorfofS-fthe housing-enclosing the-sc'aleyspii'l 3.5 anoperanng on. me torsionprmipie; ira-urbe Sui-rderstood Ythatithz-i concept underlying Lthe' pres- 4 that changes in the detailed construction and arrangement of parts thereof may be made within the range of mechanical and engineering skill Without departing from the spirit of my invention 5 as herein claimed.

What I claim is: In a balance, scale or the like, a iixed base, anioscillatable memberino'vabl relatively to said ibase, a 'dashpot-for vda-x'rpingtheoscllations of 1.0 the movable member, a housing engaging over the The scale or balance in use, is substantially the ibase and enclosing the oscillatable member and the dashpot, said dashpot comprising a cylinder "formed With an opening in one end and a plung- 'fr-'exte'clihg'i'said opening, said plunger be- 5ly'montedlo'rithelplunger for sealing the opening in the cylinder Athrough which the plunger operates, the cylinder having a screw-threaded part on the end opposite to that formed with the 20 openingjsaid cylinder being mounted on the base,

and the base having dopening a screw-thread@A JQENFRAISK Belange.

BEFQEENQES ,QU-TED y'frm following referenties aebreeordin the y ,UITEP STATES APATENr.1:.s

Pritchard #Bienne-1er 

